(a) Field of the Invention
This invention relates to a flooring system. The invention particularly (but not exclusively) concerns a ventilated flooring system, by which latter term is understood a flooring system having apertures therein, to allow the passage of gases, liquids, and also some solids therethrough, depending upon the aperture size. Such ventilated flooring systems are used for example in animal sheds and pens, because solid excreta can be forced therethrough by the animals themselves to a collection pit below the floor, leading to healthier conditions for the animals.
(b) Description of the Prior Art
There have been very many proposals for ventilated floors for livestock sheds and pens, to improve the conditions in which the animals have to live. In these proposals, it is the principal object to obtain the highest possible free air percentage--that is to say, the ratio (expressed as a percentage) of the total aperture area to the overall area of the floor--consistent with the other parameters which must be satisfied, such as strength. For instance, the floor must have sufficient strength to support the weight of the animals and must not be likely to damage the animals' feet. For example, there have been proposals for floors made from a network of round steel bars welded together at each crossing point, and though this exhibits a high free air percentage, nevertheless it can be hazardous to animals, especially those with cloven hooves, such as pigs. Also, floors of welded round bars are uncomfortable for the animals to sit or lie on, and the animals can easily slip on the bars when walking.
An added problem with ventilated floors through which animal excreta has to pass, particularly in the case of pigs, is that the excreta is most corrosive to common metals, such as iron, steel and alloys of metals such as an aluminum. Many of the previous proposals for ventilated floors for animal sheds or pens have displayed a very limited service life as a consequence. Plain steel floors, made for instance of perforated or expanded metal sheets suitably supported, have a very short service life and though this can be protracted considerably by galvanising, nevertheless the life is still not particularly long as compared for example to the life of the building in which the floor is installed. Considerable improvements can be made by coating the steel with a plastics material, for there are available plastics materials which are relatively resistant to attack by the corrosive agents in the animal excreta. However, it is found in practice that the plastics coating material can easily become chipped or scratched, leading to local corrosion of the steel substrate, followed by rapid peeling of the plastics coating material as corrosion spreads thereunder.